117 lines
3.2 KiB
Python
117 lines
3.2 KiB
Python
# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Copyright 2010 United States Government as represented by the
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# Administrator of the National Aeronautics and Space Administration.
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# All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""
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System-level utilities and helper functions.
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"""
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import sys
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from eventlet import event
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from eventlet import greenthread
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from heat.openstack.common import log as logging
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LOG = logging.getLogger(__name__)
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def chunkreadable(iter, chunk_size=65536):
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"""
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Wrap a readable iterator with a reader yielding chunks of
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a preferred size, otherwise leave iterator unchanged.
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:param iter: an iter which may also be readable
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:param chunk_size: maximum size of chunk
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"""
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return chunkiter(iter, chunk_size) if hasattr(iter, 'read') else iter
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def chunkiter(fp, chunk_size=65536):
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"""
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Return an iterator to a file-like obj which yields fixed size chunks
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:param fp: a file-like object
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:param chunk_size: maximum size of chunk
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"""
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while True:
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chunk = fp.read(chunk_size)
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if chunk:
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yield chunk
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else:
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break
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class LoopingCallDone(Exception):
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"""Exception to break out and stop a LoopingCall.
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The poll-function passed to LoopingCall can raise this exception to
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break out of the loop normally. This is somewhat analogous to
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StopIteration.
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An optional return-value can be included as the argument to the exception;
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this return-value will be returned by LoopingCall.wait()
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"""
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def __init__(self, retvalue=True):
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""":param retvalue: Value that LoopingCall.wait() should return."""
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self.retvalue = retvalue
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class LoopingCall(object):
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def __init__(self, f=None, *args, **kw):
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self.args = args
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self.kw = kw
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self.f = f
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self._running = False
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def start(self, interval, now=True):
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self._running = True
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done = event.Event()
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def _inner():
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if not now:
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greenthread.sleep(interval)
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try:
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while self._running:
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self.f(*self.args, **self.kw)
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if not self._running:
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break
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greenthread.sleep(interval)
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except LoopingCallDone, e:
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self.stop()
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done.send(e.retvalue)
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except Exception:
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LOG.exception(_('in looping call'))
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done.send_exception(*sys.exc_info())
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return
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else:
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done.send(True)
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self.done = done
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greenthread.spawn(_inner)
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return self.done
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def stop(self):
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self._running = False
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def wait(self):
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return self.done.wait()
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